A comparison of the cognitive deficits in reading disability and attention-deficit/hyperactivity disorder

This study used a nonreferred sample of twins to contrast the performance of individuals with reading disability (RD; n = 93), attention-deficit/hyperactivity disorder (ADHD; n = 52), RD and ADHD (n = 48), and neither RD nor ADHD (n = 121) on measures of phoneme awareness (PA) and executive functioning (EF). Exploratory factor analysis of the EF measures yielded underlying factors of working memory, inhibition, and set shifting. Results revealed that ADHD was associated with inhibition deficits, whereas RD was associated with significant deficits on measures of PA and verbal working memory. The RD + ADHD group was most impaired on virtually all measures, providing evidence against the phenocopy hypothesis as an explanation for comorbidity between RD and ADHD.     

Screening for attention-deficit/hyperactivity disorder in adult inpatients with psychiatric disorders

The purpose was to assess the effectiveness of the adult ADHD Module from the MINI International Neuropsychiatric Interview (MINI) and the Conners' Adult ADHD Rating Scales: Screening Version DSM-IV ADHD Symptoms Total Scale (CAARS-S:SV) in screening for attention-deficit/hyperactivity (ADHD) disorder in patients hospitalized for other psychiatric disorders. Assessment measures were administered to 55 (50%) female and 55 (50%) male adult (>18 yr. old) inpatients. Only six (5%) of the 110 inpatients had been diagnosed with comorbid ADHD according to medical charts. In contrast, 55 (50%) patients met criteria for ADHD according to the MINI, and 39 (36%) patients met criteria on the CAARS-S:SV. The higher rates of prevalence for the MINI and the CAARS-S:SV were attributable to symptom criteria for ADHD being similar to those shared with comorbid disorders.     

自闭症谱系障碍个体的社会动机缺陷

自闭症谱系障碍(ASD)是一种源于儿童期的神经发育障碍, 社会交往障碍是其核心特征, 与社会动机缺陷密切相关。社会动机是引导个体社会行为的强大动力, 主要表现为社会定向、社会奖赏和社会维持。现有研究表明, ASD个体的社会动机发展存在缺陷, 他们对社会刺激的注意偏向减少, 不能主动寻求和体会社会互动带来的快乐, 且缺乏维持社会关系的行为策略等。然而, 相关研究结果受到个体特征、环境和实验设计等因素的影响。研究者未来应综合考虑这些影响因素, 加强对ASD个体社会动机理论的整合研究, 以便全面系统地了解ASD个体的社会动机缺陷。     

Stimulus-dependent dopamine release in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the autoreceptors so that stimuli-evoked phasic dopamine is boosted. The authors propose that these boosted phasic responses yield hypersensitivity to environmental stimuli in ADHD. Stimuli evoking moderate brain arousal lead to well-functioning performance, whereas either too little or too much stimuli attenuate cognitive performance. Strong, salient stimuli may easily disrupt attention, whereas an environment with impoverished stimuli causes low arousal, which is typically compensated for by hyperactivity. Stochastic resonance is the phenomenon that makes a moderate noise facilitate stimulus discrimination and cognitive performance. Computational modeling shows that more noise is required for stochastic resonance to occur in dopamine-deprived neural systems in ADHD. This prediction is supported by empirical data.     

孤独症谱系障碍者的视觉-空间工作记忆缺陷及脑机制

孤独症谱系障碍(ASD)个体存在视觉-空间工作记忆加工缺陷,主要表现在4个方面,即随认知负荷增大而缺陷加重、工作记忆容量不足、工作记忆加工过程中的注意功能失调和对刺激进行整体组织的能力缺乏。神经机制研究显示,ASD个体存在明显的额-顶工作记忆网络激活异常,以及相关脑区的脑结构、白质连接异常。另外,作为基础性的认知加工过程,ASD个体的视觉-空间工作记忆各加工环节与言语工作记忆、执行功能、社会认知等因素均存在交互影响。纵观目前研究成果,未来研究可从研究手段、机制探究和干预训练三方面入手,着眼于研究方法的生态化和多元化,揭示客体和空间工作记忆的机制分离,并着力开发更具针对性的干预训练模式。     

Neurocognitive functioning in adults with attention-deficit/hyperactivity disorder

The performance of nine adults with attention-deficit/hyperactivity disorder (ADHD) was compared with the performance of 23 normal controls on computerized measures of target orientation, sustained attention, encoding speed, and motor output/response organization to determine the nature of the neurocognitive deficits of adults with ADHD. While the groups' performances on measures of sustained attention and encoding speed did not differ, significant group differences were seen on a task that targeted motor output/response organization. These data suggest that the neurocognitive difficulties of ADHD adults are not related to a primary deficit in sustained attentional functioning. Rather, the deficient information processing in ADHD adults is related to difficulties with motor output/response organization.     

Gait control in children with attention-deficit/hyperactivity disorder

The current profile of gait control in children with ADHD is incomplete and predominately based on children walking forward at a self-selected pace. There are no studies of potential gait deficits in this clinical population when walking in different directions in combination with varying rates of stepping that are freely selected and entrained to an external stimulus. The purpose of the current study was to address this lack of information by assessing gait of children aged 7–17 years with (n = 17) and without (n = 26) ADHD. Participants walked forward and backward along an electronically instrumented carpet at a self-selected stepping rate and in synchrony to a metronome that dictated an increased and decreased stepping rate. Using repeated measures analysis of covariance (ANCOVA) to assess spatiotemporal gait parameters, results showed that children with ADHD exhibited a significantly exaggerated, toes ‘turned out,’ foot position for all walking conditions compared to typically developing children. When walking backward, children with ADHD produced an increased step width, higher stepping cadence, and increased velocity. Additionally, coefficient of variation ratios indicated that children with ADHD produced greater variability of velocity, cadence, and step time for all walking conditions, and greater variability for stride length when walking at an increased stepping rate. Results were interpreted in terms of clinical significance and practical ramifications that inform rehabilitation specialists in designing therapies that ameliorate the reported gait deficits.     

Parenting in mothers with and without attention-deficit/hyperactivity disorder

The authors examined the impact of maternal attention-deficit/hyperactivity disorder (ADHD) on parenting behaviors. Sixty mothers between the ages of 31 and 50 with (n = 30) and without (n = 30) ADHD and their 8- to 14-year-old children with ADHD completed self-report and laboratory measures of monitoring of child behavior, consistency in parenting, and parenting problem-solving abilities. These parenting behaviors were selected because of their established links to the development of child behavior problems. As predicted, mothers with ADHD were found to be poorer at monitoring child behavior and less consistent disciplinarians compared with mothers without ADHD. There was some evidence to support the prediction that mothers with ADHD were less effective at problem solving about childrearing issues than control mothers. The differences between the 2 groups of mothers persisted after child oppositional and conduct-disordered behavior were controlled. These results indicate that parenting is an area of functioning that requires more attention in adult ADHD research.     

Adult attention-deficit/hyperactivity disorder: neuropsychological correlates and clinical presentation

We compared the neuropsychological test performance of adult ADHD patients to the neurocognitive profiles of control subjects recruited from the general population. We administered a neuropsychological test battery consisting of measures considered sensitive to either orbitofrontal or dorsolateral-prefrontal (DLPF) dysfunction. Orbitofrontal hypoarousal is associated with behavioral disinhibition and a relative indifference to punishment. The DLPF region may function as a central executive system. Indeed, DLPF dysfunction may underlie many of the cardinal symptoms associated with ADHD. We tested the following hypotheses: (1) adult subjects meeting DSM-IV criteria for ADHD, predominantly hyperactive-impulsive type, would display neuropsychological deficits on tasks sensitive to orbitofrontal dysfunction; (2) adult subjects meeting DSM-IV criteria for ADHD, predominantly inattentive type, would perform poorly on measures sensitive to DLPF dysfunction; and (3) adult subjects meeting DSM-IV criteria for ADHD, combined type, would exhibit performance deficits on orbitofrontal measures and on DLPF tasks. Results partially confirmed our hypotheses. Subtyping ADHD patients revealed important group differences. Distinct neurocognitive and clinical profiles were observed.     

Cognitive inhibition and working memory in attention-deficit/hyperactivity disorder

Studies of cognitive control in attention-deficit/hyperactivity disorder (ADHD) have emphasized the ability to suppress motor responses (i.e., behavioral inhibition) rather than the ability to actively suppress prepotent mental representations (i.e., cognitive inhibition). Further, working memory deficits are suspected in ADHD, yet their distinction from cognitive inhibition is unclear. Two hundred and eighty-eight adolescent and adult participants, 115 of whom met criteria for ADHD and 173 of whom were for non-ADHD comparison, completed a sentence processing task that required the suppression of an incorrect interpretation and a working memory task. The results failed to support cognitive inhibition problems in ADHD. Moreover, the ability to reanalyze sentences with a temporary misinterpretation was at least partially related to working memory performance. The results challenge a unitary inhibition problem in ADHD and suggest inhibition problems do not extend to cognitive suppression in this age range.     

Gist-based illusions within and across stimulus modalities in autism spectrum disorder

Some studies have reported a low rate of false recognition (FR) in individuals with autism spectrum disorder (ASD) relative to non-autistic comparison participants (CPs). This finding, however, has not always been replicated and the source of the discrepancy remains unknown. We hypothesised that poor episodic memory functions may account for this finding. We used an adapted version of the Deese, Roediger and McDermott paradigm which presents lists of words, pictures or word–picture pairs to obtain measures of performance which reflect episodic [hits and false alarms (FAs)] and semantic (FR) memory functions. Results showed a decreased rate of FR in ASD individuals with lists of words which rose above the rate seen in non-autistic CPs with lists of word–picture pairs. This increased rate of FR in ASD was accompanied by a parallel increase in hits and a decrease in FA which reached a similar level in the two groups. Poor episodic memory functions may prevent individuals with ASD from acquiring item information which in turn precludes the formation of semantic links between items. This could render them less prone to FR.     

Trait mechanisms in youth with and without attention-deficit/hyperactivity disorder

Relations of temperament and personality traits within children and adolescents with ADHD and non-ADHD controls were examined. A two-process structure was hypothesized involving top-down effortful and bottom-up reactive response tendencies. Top-down processes were hypothesized to relate to inattentive ADHD symptoms, whereas bottom-up processes were hypothesized to relate to hyperactive–impulsive ADHD symptoms. Each hypothesis was tested in a sample of 179 children age 7–13 (113 boys; 107 ADHD) and then replicated in 184 adolescents age 14–17 (109 boys; 87 ADHD). All families completed a multistage diagnostic process. Youth completed laboratory measures of cognitive control, and parents completed trait ratings. Traits examined in the current study included effortful control, reactive control, resiliency, negative emotionality, neuroticism, extraversion, openness, agreeableness, and conscientiousness. Correlational relations among traits were inconclusive, but external correlations with cognitive tasks and ADHD symptoms were interpretable within the hypothesized two-process framework. Results provide partial support for a distinction between effortful and reactive traits and suggest this distinction is useful in relation to understanding ADHD.     

社会动机理论视角下自闭症谱系障碍者的社交缺陷

社交缺陷是自闭症谱系障碍的核心症状。以往研究更多从社会认知的角度指出该症状是心理理论损伤所致, 但自闭症谱系障碍个体在获得心理理论之前已表现出社会动机不足的特质, 且部分能通过心理理论测试的个体依旧表现出社会动机不足的特点。社会动机理论指出社会动机是促进人类进化、激发和维持个体社会性活动的重要内部动力, 自闭症谱系障碍者的社交缺陷是由于社会动机不足所致。该理论从行为表现、神经科学和生物学三个方面对自闭症谱系障碍者的社交缺陷进行解释。未来应进一步完善自闭症谱系障碍个体社会动机的神经机制研究, 明确社会动机理论在自闭症谱系障碍群体中的适用范围, 探究社会动机理论在评估诊断和临床康复中的应用价值。     

γ节律神经振荡：反映自闭症多感觉整合失调的一项重要生物指标

多感觉整合是对不同感官信息进行选择、联系、统一乃至解释的加工过程, 它需要神经系统不同功能区域的共同投入与相互协调, 以实现多种感觉信息的时间捆绑以及全局性的预测编码。而γ神经振荡因具有反映神经皮层兴奋/抑制的平衡状况, 实现多感官信息的时间同步, 以及通过跨频耦合实现全局性预测编码的特点, 在多感觉整合的加工过程中发挥着重要作用。相比正常个体, 自闭症患者神经系统中的GABA中间神经元存在结构与功能异常, 导致γ神经振荡紊乱, 由此破坏了正常的时间同步以及预测编码加工, 并最终引发多感觉整合失调。基于上述因果关联, 未来研究可结合无创可逆性干预技术, 以γ节律神经振荡为生物反馈指标, 形成科学系统化的临床干预治疗方案。     

Autonomic correlates of attention-deficit/hyperactivity disorder and oppositional defiant disorder in preschool children

Numerous studies have revealed autonomic underarousal in conduct-disordered adolescents and antisocial adults. It is unknown, however, whether similar autonomic markers are present in at-risk preschoolers. In this study, the authors compared autonomic profiles of 4- to 6-year-old children with attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD; n = 18) with those of age-matched controls (n = 20). Children with ADHD and ODD exhibited fewer electrodermal responses and lengthened cardiac preejection periods at baseline and during reward. Although group differences were not found in baseline respiratory sinus arrhythmia, heart rate changes among ADHD and ODD participants were mediated exclusively by parasympathetic withdrawal, with no independent sympathetic contribution. Heart rate changes among controls were mediated by both autonomic branches. These results suggest that at-risk preschoolers are autonomically similar to older externalizing children.     

Adaptive skills and executive function in autism spectrum disorders.

There is active debate regarding the nature of executive dysfunction in autism. Additionally, investigations have yet to show a relationship between deficits in executive function and the everyday behavioral difficulties that may originate from them. The present study examined the relationship between executive abilities and adaptive behavior in 35 children with Autism Spectrum Disorders, using two parent reports of everyday functioning, the Vineland Adaptive Behavior Scales (VABS) and the Behavior Rating Inventory of Executive Function (BRIEF). Results found several relationships: The Initiate and Working Memory domains were negatively correlated with most domains of adaptive behavior. Also, the Communication and Socialization domains of the VABS were negatively correlated with several areas of executive functioning, suggesting that impairments in executive abilities are strongly associated with the deficits in communication, play and social relationships found in children with autism.     

Cross-lateralisation in children with attention-deficit/hyperactivity disorder and motor skill performance

Cross-lateralisation and increased motor difficulties have been reported in children with attention-deficit/hyperactivity disorder (ADHD). Nevertheless, the question of how crossed (i.e. mixed preference) or uncrossed (i.e. same side preference) lateralisation impacts motor performance in children with ADHD has yet to be examined. In this study, previously validated observational measures of hand and foot preference were used to identify right-handed children with ADHD who display cross- (n = 29) and uncross-lateralisation (n = 31). An uncross-lateralised typically developing (TD) group (n = 32) was also identified, and included as a control. Motor performance was assessed with seven valid and reliable fine and gross motor tasks performed with both preferred and non-preferred limbs. Group, task and sex-related effects were examined. Findings revealed that male (but not female) cross-lateralised children with ADHD performed significantly worse, respectively, in two of the fine motor tasks (spiral tracing [p < .01], and dot filling [p < .05]). Results suggest that cross-lateralised hand and foot preference may affect complex motor skills in male children with ADHD. Furthermore, characteristics of ADHD may manifest differently in male and female children. Findings highlight the importance of considering both hand and foot preference when targeting motor interventions for children with ADHD.     

Sustained attention and executive functioning performance in attention-deficit/hyperactivity disorder.

The aim of this study was to further refine the cognitive phenotype of attention-deficit/hyperactivity disorder (ADHD), with respect to the ability to sustain attention and executive functioning. Participants were 34 boys with ADHD (combined type) and 28 normal controls. The groups were closely matched for age and IQ. All participants were 12 years of age. Both groups performed a computerized sustained attention task and a response interference task. Measures related to speed, accuracy, and time on task were collected. We found that children with ADHD performed slower, less accurately, more impulsively, and with less stability than controls. Both groups produced more errors with increasing time on task, reflecting reduced vigilance. Importantly, no interaction with time on task was found. The overall pattern of results suggests that measures related to accuracy are more informative than measures related to speed of responding in refining the cognitive phenotype of ADHD.